I. Field of the Invention
This invention relates generally to apparatus for treating stenotic lesions on the interior walls of blood vessels, and more particularly to a device useable during a balloon angioplasty procedure for treating the site so as to reduce the incidences of restenosis.
II. Discussion of the Prior Art
In the Clarke et al. U.S. Pat. No. 5,053,033, there is described a method and apparatus for reducing the proliferation of smooth muscle cells in the blood vessel walls at an angioplasty site by irradiating it with UV radiation. In accordance with the teachings of the Clarke et al. patent, the UV radiation is delivered to the angioplasty site by way of an optical fiber or other waveguide incorporated into a percutaneous catheter, which is preferably a balloon angioplasty catheter having a lumen through which the laser fiber is inserted, After the balloon has been inflated to increase the lumenal diameter of the vessel, the balloon is deflated and the catheter backed off a short distance in the proximal direction so as to position the distal end of the optical fiber at a location so that UV light transmitted through the optical fiber and emanating from its distal end will impinge upon the angioplasty treatment site,
Reissue U.S. Pat. No. 34,544 to Spears also describes a method for treatment of an artery or other blood vessel containing etherosclerotic plaque in which a drug, hematoporphyrin, is injected and absorbed into the plaque. Subsequently, the site is illuminated from an external light source connected to the proximal end of an optical waveguide. A light diffusing device coupled to the distal end of the waveguide and contained within the balloon itself disperses the light uniformly over a portion of the area occupied by the balloon.
Optical fibers, by their very nature, are brittle and small in diameter, have very poor flexural modulus, column strength and torqueability. This makes it difficult to pass them through a lumen, such as a guidewire lumen, of a conventional balloon angioplasty catheter.
It is accordingly a principal object of the present invention to provide a new and improved device for applying UV radiation to the site of a stenotic lesion that has been opened by an interventional technique such as in a balloon angioplasty procedure.
Another object of the invention is to provide a light emitting device that may be readily passed down the guidewire lumen of a conventional balloon catheter.